Apparatus for use in pelletizing ore

ABSTRACT

An improved apparatus for pelletizing ore includes a balling device which forms green pellets. A pellet hardening assembly heats the green pellets and then indurates the pellets to a desired hardness. The hardened pellets are transferred to a cooling tower where they are cooled prior to being discharged onto a receiving conveyer. The cooling tower includes a stationary upper section and a rotatable lower section. In accordance with a feature of the present invention, a water seal is provided between the stationary upper and the rotatable lower section of the tower. The water seal includes an annular trough which holds a body of water which circumscribes the outer wall of the lower section of the cooling tower. A circular baffle wall connected with the stationary upper section of the tower extends downwardly into the water in the trough to prevent the escape of gas and other pollutants from the interior of the tower. The space between the upper and lower sections of the tower is pressurized to retard any tendency for gas and dust or other materials to flow toward the seal.

United States atent [191 [111 3,860,224 Urich Jan. 14, 1975 APPARATUS FOR USE IN PELLETIZING ORE [57] ABSTRACT [75] Inventor: Daniel M. Urich, Hibbing, Minn. An improved apparatus for pelletizing ore includes a balling device which forms green pellets. A pellet [73] Asslgnee' i Tacomte Company Forbes hardenin assembl heats the reen ellets and then Mmn g y g P indurates the pellets to a desired hardness. The hard- [22] Filed: Oct. 19, 1973 ened pellets are transferred to a cooling tower where they are cooled prior to being discharged onto a re- [21] App1N0"407777 ceiving conveyer. The cooling tower includes a stationary upper section and a rotatable lower section. In [52] US. Cl 266/20, 34/242, 214/35 R accordance with a feature of the present invention, a [51] Int. Cl. F271) 7/32 water seal is provided between the stationary upper [58] Field of Search 266/9, 20, 21; 432/77, and the rotatable lower section of the tower. The 432/117; 75/3; 34/134, 174, 242; 214/35 R water seal includes an annular trough which holds a body of water which circumscribes the outer wall of [56] References Cited the lower section of the cooling tower. A circular baf- UNlTED STATES PATENTS fle wall connected with the stationary upper section of 2 799 489 7/1957 Rusche 432/117 the tower extends downwardly into the water in the 2 861 356 11/1958 Lene ..I:III IIIIIII II 432/117 trough Prevent the escape of gas and other Pollut' 2:925:336 2/1960 Stowasser 75/3 ants from the interior of the fewer- The Space between 3,188,195 6/1965 Price 75/3 the upper and 10Wer Sections of the tower is pressur- 3,554,511 1/1971 Wald... 34/242 ized to retard any tendency for gas and dust or other 3,732,993 5/1973 Csapo 34/242 materials to flow toward the seal.

Primary Examiner-Gerald A. Dost 3 Claims, 3 Drawing Figures PATENTEDJAHI 41975 FIGI APPARATUS FOR USE IN PELLETIZING ORE BACKGROUND OF THE INVENTION Taconite and other ores which require processing at very fine sizes are commonly agglomerated by a pelletizing process wherein green or wet pellets are formed and then fired or indurated to a desired hardness. Green or wet taconite pellets are formed by crushing crude ore, grinding the crude ore to a fine size (approximately 325 mesh), concentrating the ore magnetically, adding bentonite to the wet concentrate, dewatering the ore and rolling or balling the ore to form generally spherical green or wet pellets. The green or wet pellets are then transferred to an indurating or hardening machine. The hardening machine dries and preheats the green or wet pellets before indurating or final firing in a kiln. The hot hardened pellets are transferred from the final firing kiln to a cooling tower where they are cooled to a relatively low temperature before being deposited onto a receiving conveyer.

A known type of cooling tower includes a stationary upper section which is connected with the final firing kiln and a rotatable lower section. The pellets from the final firing kiln pass through an opening in the upper section and onto a grate on the rotatable lower section. Sand seals have previously been utilized to prevent the escape of gases from between the upper and lower sections of the tower.

SUMMARY OF THE PRESENT INVENTION The present invention provides an apparatus for use in pelletizing ore and in which a liquid seal is provided between relatively movable sections of a cooling tower. A stationary upper section of the cooling tower is connected with the final firing kiln. A rotatable lower section of the tower receives the pellets from the upper section. An annular trough holds a body of water or other liquid which circumscribes the outer wall of the rotatable lower section of the tower. A circular baffle wall extends downwardly from the stationary upper section of the cooling tower into the annular body of water to prevent the escape of gases and other materials from between the two sections of the tower. To retard a flow of gases and other materials toward the water seal, air or other fluid under pressure is conducted to the area adjacent the water seal.

Accordingly, it is an object of this invention to provide a new and improved apparatus for use in pelletizing ore and wherein a cooling apparatus for receiving hardened pellets includes relatively movable upper and lower sections and a liquid seal between the two sections.

Another object of this invention is to provide a new and improved apparatus for use in pelletizing ore and wherein a cooling device which receives the hardened pellets includes a stationary upper portion having a circular cross section, a rotatable lower portion which receives the hardened pellets, an annular trough connected with the lower portion to hold a body of liquid which circumscribes the lower portion of the cooling tower, and a circular baffle wall which is connected with the upper portion of the tower and extends downwardly into the body of liquid to seal a space between the upper and lower portions of the cooling device.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects and features of the present invention will become more apparent upon a consideration of the following description taken in connection with the accompanying drawings wherein:

FIG. 1 is a schematic illustration of a pelletizing apparatus having a cooling tower constructed in accordance with the present invention;

FIG. 2 is an enlarged schematic sectional view, taken generally along the line 2-2 of FIG. 1, illustrating the relationship between relatively movable upper and lower sections of the cooling tower; and

FIG. 3 is an enlarged sectional view illustrating the relationship between a water or liquid seal and the sections of the cooling tower.

DESCRIPTION OF ONE SPECIFIC PREFERRED EMBODIMENT OF THE INVENTION While it is contemplated that the apparatus forming the subject matter of the present invention will be used in pelletizing plants processing many different types of pellets, the present invention is particularly well adapted to iron ore pelletizing processes wherein finely divided iron ore particles are formed into pellets which are hardened so that they can be utilized as a part of the charge of a blast furnace. Due to its low quality, the iron ore called taconite and found in the Mesabi Range is particularly well suited to beneficiation by a pelletizing process. This pelletizing process includes the general steps of forming green or wet pellets, firing or indurating the green pellets to a desired hardness, and cooling the pellets.

A pelletizing apparatus 10 forming taconite pellets is illustrated in FIG. 1 and includes a balling device 12 which forms crushed and magnetically concentrated taconite ore into small, generally spherical shapes by a snow-balling technique during what is commonly called a balling step in which green or wet pellets of from 5/16 of an inch to l /2 inches in diameter are formed. The green or wet pellets are heat treated or indurated to a desired hardness in an indurating or hardening apparatus 14. The indurating or hardening apparatus 14 is, in the present instance, of the traveling-grate kiln type and has an input 16 where green or wet pellets are received in a drying furnace 18. The green or wet pellets are moved through the drying furnace 18 to a preheating furnace 22 by a traveling grate or conveyer 24. The green or wet pellets are heated to a temperature of 200 to 800 in the drying furnace 18 before passing on into the preheating furnace 22 where they are heated to a temperature of from l200F to 2l00F.

The heated pellets are dumped from the conveyer 24 onto a transfer apparatus 30 which conducts the pellets to a rotary indurating kiln or final firing section 34. R0- tation of the kiln 34 causes the dry or preheated pellets to move downwardly through the kiln as they are fired or heated to a temperature of approximately 2400F under the influence of a heat source 40. This firing of motor 54. A fan 56 blows air under pressure into the lower section 52 of the cooling tower 50.

In accordance with the present invention, a liquid or water seal 60 is provided between the relatively movable upper and lower sections 50 and 52 of the cooling tower 44. The liquid seal 60 includes an annular trough 64 (FIG. 2) which is mounted on a cylindrical refractory lined outer wall 66 of the lower section of the cooling tower. The trough 64 holds an annular body of water or other liquid which circumscribes the outside of the wall 66. An annular baffle wall 70 is fixedly connected with the stationary upper section 50 of the cooling tower 44 and extends downwardly into the annular body of water 74 in the trough 64. The annular wall 70 cooperates with the body of water 74 to form a fluid tight seal between the stationary upper section 50 of the cooling tower and the rotatable lower section 52.

During operation of the pelletizing apparatus 10, hot iron ore pellets 78 move from the final firing section 34 into the cooling tower 44 through a circular opening 82 in a cylindrical wall 84 of the stationary upper section 50 of the cooling tower. The pellets fall from the opening 82 onto a grate or bed (not shown) in the movable lower section 52 of the cooling tower 44. As this is occurring, the drive motor 54 is effective to rotate the lower section 52 relative to the upper section 50. As the lower section 52 of the cooling tower is rotated, the trough 64 is rotated relative to the stationary wall 70. Since the trough 64 is rotated about a vertical axis, the cylindrical baffle wall 70 remains in the body of water 74 to prevent the escape of gases through a circular opening 88 between the two sections of the cooling tower.

The trough 64 has an annular outer wall 92 (see FIG. 3) which extends parallel to the cylindrical wall 66 of the lower section 52 of the cooling tower 44. The baffle wall 70 also extends parallel to the cylindrical outer wall 66 and is disposed approximately midway between the inner and outer walls. Therefore, when the lower section 52 of the cooling tower is rotated relative to the upper section 50, the trough 64 is rotated relative to the wall 70 about the central vertical axis of the cooling tower 44 and the wall 70 remains in the center portion of the annular body of water 74. Water can be added to the trough 64 by operating a valve 96 to enable water to flow from a supply pipe 98 into the trough.

During operation of the pelletizing apparatus, it is contemplated that gases and/or particles of material may tend to flow toward the opening 88 between the two sections of the cooling tower 44. To retard this flow of gases or other materials, an air supply 102 (see FIG. 3) is effective to pressurize the area adjacent to the circular opening 88. The air supply apparatus 102 includes a manifold conduit 104 which is connected with a supply of air under pressure and a plurality of pipes 106 which conduct the air from the manifold 104 through openings 108 (FIG. 3) in the annular wall 70. Although only one pipe 106 has been shown in FIG. 3, it should be understood that there are a plurality of pipes which extend through the baffle walls 70 at spaced apart locations in the manner illustrated schematically in FIG. 2. Since the area adjacent to the top of the liquid 74 in the trough 64 is pressurized by air from the pipes 106, gases, dust, and other materials tend to flow inwardly away from the trough 64 so that there is minimal or no leakage from the cooling tower 44 as the lower section is rotated relative to the upper section 50. For example, the pressure supplied to the manifold is about 3 to 18 inches of water greater than the pressure in the interior of the cooling tower 44.

In view of the foregoing description, it can be seen that the pelletizing apparatus 10 includes a cooling tower 44 having a stationary upper section 50 which is connected with a final firing kiln 34. A lower section of the cooling tower is rotated by a drive motor 54 and receives hot hardened pellets from the kiln 34. An annular trough 64 holds a body of water 74 which circumscribes the outer wall 66 of the movable lower section 52. The cylindrical baffle wall extends downwardly from the upper section 50 into the annular body of water 74 to prevent the escape of gases and other material through the space 88 between the two sections of the cooling tower. To retard a flow of gases and other materials toward the opening 88, it is pressurized by air from the manifold 104.

Having described one specific preferred embodiment of the invention, the following is claimed:

1. An apparatus for use in pelletizing ore comprising balling means for forming green pellets, a pellet hardening assembly for processing green pellets from said balling means to form pellets of a desired hardness, said hardening assembly including means for heating the pellets and indurating the pellets to a desired hardness, and cooling means for receiving hardened pellets from said hardening assembly and for cooling the hardened pellets, said cooling means including a stationary upper portion, said stationary upper portion having a stationary main wall with a circular lower end portion, said cooling means further including a movable lower portion which receives the hardened pellets, said movable lower portion having a movable main wall with a circular upper end portion disposed adjacent to and spaced apart from the lower end portion of the main wall of said upper portion to form an annular opening between said upper and lower portions, annular trough means connected with said lower portion for holding an annular body of liquid which circumscribes said main wall of said lower portion, a circular sealing wall fixedly connected with said upper portion and extending downwardly across said annular opening and into the annular body of liquid, means for rotating said lower portion and said trough means containing the annular body of liquid relative to said stationary upper portion, and means for directing a flow of air inwardly through the annular opening between the upper end portion of said lower main wall and the lower end portion of said upper main wall to retard the movement of gas and solids toward said trough means through the annular opening.

2. An apparatus as set forth in claim 1 wherein said means for directing a flow of air through the annular opening includes a plurality of conduits extending radially inwardly through said sealing wall, said conduits having openings disposed outwardly of said upper and lower main walls and facing toward the annular opening between said upper and lower main walls to enable said conduits to direct a flow of air inwardly through the annular opening.

3. An apparatus as set forth in claim 1 further including means for supplying liquid to said trough means. 

1. An apparatus for use in pelletizing ore comprising balling means for forming green pellets, a pellet hardening assembly for processing green pellets from said balling means to form pellets of a desired hardness, said hardening assembly including means for heating the pellets and indurating the pellets to a desired hardness, and cooling means for receiving hardened pellets from said hardening assembly and for cooling the hardened pellets, said cooling means including a stationary upper portion, said stationary upper portion having a stationary main wall with a circular lower end portion, said cooling means further including a movable lower portion which receives the hardened pellets, said movable lower portion having a movable main wall with a circular upper end portion disposed adjacent to and spaced apart from the lower end portion of the main wall of said upper portion to form an annular opening between said upper and lower portions, annular trough means connected with said lower portion for holding an annular body of liquid which circumscribes said main wall of said lower portion, a circular sealing wall fixedly connected with said upper portion and extending downwardly across said annular opening and into the annular body of liquid, means for rotating said lower portion and said trough means containing the annular body of liquid relative to said stationary upper portion, and means for directing a flow of air inwardly through the annular opening between the upper end portion of said lower main wall and the lower end portion of said upper main wall to retard the movement of gas and solids toward said trough means through the annular opening.
 2. An apparatus as set forth in claim 1 wherein said means for directing a flow of air through the annular opening includes a plurality of conduits extending radially inwardly through said sealing wall, said conduits having openings disposed outwardly of said upper and lower main walls and facing toward the annular opening between said upper and lower main walls to enable said conduits to direct a flow of air inwardly through the annular opening.
 3. An apparatus as set forth in claim 1 further including means for supplying liquid to said trough means. 